Mexican women, particularly those who work in high-risk professions, are over represented in the number of reported cases of a variety of STDs. The dramatic increase in STDs among working women has occurred primarily in border cities. The development of risk reduction interventions tailored to women has become a priority, yet limited resources in the host country have prevented the funding of prevention programs. Over the past 18 months, researchers from the University of California, San Diego and the Universidad Autonoma de Baja California collaborated on a pilot study that examined the feasibility of delivering a cultural and population-sensitive counseling program to women attending a municipal health clinic specializing in STDs in Tijuana, Mexico. Findings from this pilot study suggest the feasibility of testing the effectiveness of our Spanish version STD risk reduction counseling program - with a broad based population of women who reside in border cities in Mexico. We have also added a team of well-established Latino researchers with expertise in Mexican origin/Latino health, specifically as it relates to behavioral health issues and the impact of Mexican origin/Latino identity formation and acculturation on health outcomes. The proposed five year study will utilize a four city design that includes two pairs of treatment-comparison cities ranging in size from 400,000 to 1.2 million. The four border cities include Tijuana, Ciudad Juarez, Mexicali, and Matamoros. Pairs of cities will be randomly assigned to a treatment or comparison condition. Our study design will compare the effects of our STD counseling program for in treatment cities (N=900) against a "standard counseling" condition (N=900) in comparison cities. Behavior outcomes will be assessed over a six-month period. The design of the counseling program was guided by motivational interviewing, social cognitive theory, and the theory of reasoned action. Repeated measures analysis of variance will be used to evaluate the effectiveness of the intervention. Subgroup differences in the effectiveness of the intervention based on social, contextual, and interpersonal factors will be explored.